Mg—Al—Ca alloys have been mainly developed as die-cast materials. When an excessive amount of Al or Ca which is a solute element is added, a hard compound is formed to thereby give a brittle magnesium alloy, and thus it has not been possible to obtain excellent mechanical properties.
Accordingly, although magnesium alloys having low addition amounts of Al and Ca have been developed, the strength thereof has not been improved. Under the above circumstances, with respect to the researches on Mg—Al—Ca alloys, researches on phases to be formed and researches on only Mg—Al—Ca alloys having extremely low addition amounts of Al and Ca are often performed.
Furthermore, in order to make magnesium alloys commercially available, it is necessary to enhance flame resistance and to increase the ignition temperature thereof. However, when the flame resistance is enhanced, the mechanical properties are often lowered, and the flame resistance and the mechanical properties are in the relation of trade-off, with the result that it is difficult to enhance both of them.
Moreover, in order to make magnesium alloys commercially available, the enhancement of corrosion resistance is also required.